1. Technical Field of the Invention
The present invention relates to systems and methods for packaging tortillas, and more particularly, to systems and methods for the transfer of stacks of tortillas from counting and stacking assembly lines to bagging operation.
2. Description of Related Art
The commercial production of tortillas requires a series of operations which are traditionally accomplished using manual labor, because no machinery has not been designed to take over these tasks. However, as the popularity of the tortilla grows, competitive business conditions mandate the automation of production lines wherever possible, including the automated packing of stacks of tortillas.
After cooking in an oven, several rows or xe2x80x9ctracksxe2x80x9d of freshly-cooked tortillas enter into a cooling apparatus where the heat from cooking is rapidly removed. At this point, the tortillas are ready for packaging. However, before this is accomplished, the individual tortillas must be gathered together in stacks of preselected sizes for insertion into bags. While there are automated machines to count and stack the tortillas, the individual stacks which result are currently brought to the packaging machinery by means of manual labor. Thus, for example, a four-track counting-stacking production line requires two laborers to remove the stacks of tortillas and place them on a single conveyor line for packaging.
The system of manual labor to transfer tortilla stacks from the counter-stacker apparatus to packaging machinery requires personnel dedicated to this task. Disadvantages include higher work costs, laborer fatigue, and physical contact between the laborers and the tortillas.
The use of manual labor is not entirely without advantages, however. Laborers are able to precisely place the stacks of tortillas on packaging infeed conveyors, facilitating smooth bagging operations. Further, human operators are also able to ensure that the packaging infeed conveyors are filled to capacity, within the limits of the production line. That is, four tracks of tortilla stacks produced by a counter-stacker apparatus can be smoothly transitioned to a single packaging infeed conveyor belt using human operators. Such operators efficiently fill the infeed conveyor with tortilla stacks such that the minimum number of xe2x80x9cemptyxe2x80x9d conveyor belt blocks, or spaces arrive at the packaging apparatus. Therefore, what is needed, is a system and method for tortilla stack transfer which is automated, and provides all of the advantages of human laborers. More particularly, the automated system and method for tortilla stack transfer should operate to lower work costs, reduce the fatigue of manual laborers, and increase the overall cleanliness of tortilla handling operations. Further, the system and method should efficiently transfer stacks of tortillas to the bagger infeed conveyor, such that the maximum number of empty positions on the conveyor are filled, within the limits of the production line supply.
The counter-stacker structure manages a plurality of tortilla stacks, typically arranged in rows. However, the bagger infeed conveyor requires arranging the stacks into a single row. To solve this problem, the counter-stacker structure is placed in parallel with the tortilla stack transfer system of the present invention so that the rows of tortilla stacks can be transformed into a single row which fills the bagger infeed conveyor.
The tortilla stack transfer system for moving a plurality of tortilla stacks from a counter-stacker machine structure to a packaging area comprises a plurality of transfer stack supports adapted to operate in sliding relationship with a corresponding plurality of transfer finger sets which can be actuated to move from a loaded position, to an unloaded position, and back again. Typically, the stack supports have a curved wall with predefined openings which are penetrated by the transfer finger sets. A transfer conveyor is located beneath the transfer finger sets and carries a plurality of serially-placed conveyor blocks. A block position detector (e.g. a photocell) is adapted to sense the initial position of each one of the blocks as it moves along the transfer conveyor, and a conveyor position counter (e.g. an encoder) provides a movement position signal related to the initial position of each block as it moves from the initial position toward the transfer finger sets.
A processor determines when a particular conveyor block is proximate to one of the transfer finger sets, and commands the loaded finger set to unload a stack of tortillas onto the proximate conveyor block. The conveyor blocks are typically spaced apart from each other on the conveyor according to a preselected distance, which may be approximately equal to the width of the tortilla stacks. The processor is in electrical communication with the finger set actuators, the block position detector, and the conveyor position counter.
The system may include a plurality of compacting discs and actuators; one disc and actuator per transfer stack support. The discs move to compress each tortilla stack against the corresponding transfer finger set as the tortillas are moved off of the transfer finger set onto the selected conveyor block. This gives the stack some additional cohesion which maintains the stack arrangement as it falls onto the selected conveyor block of the moving transfer conveyor.
The invention includes a method of moving a plurality of tortilla stacks from a counter-stacker machine to a packaging area, comprising the steps of receiving a first stack of tortillas above a loading zone, sensing an initial position of a moving conveyor block which passes through the loading zone, sensing the moving position of the conveyor block in relation to the initial position, determining that the block has entered the loading zone, and moving the stack of tortillas onto the conveyor block. Typically, the initial position is located in a fixed spacial relationship with the loading zone, which is located elevationally below each one of the transfer finger sets, and is created when a selected empty conveyor block comes into vertical alignment with the loaded transfer finger set.
Typically, the step of receiving includes loading the stack of tortillas onto a transfer finger set, and the step of moving the stack of tortillas onto the conveyor block includes the step of moving the transfer fingers from a loaded position to an unloaded position. The steps of sensing the initial and moving positions of the conveyor block are usually accomplished using a photocell and encoder, respectively. The photocell detects the initial position of the block, and the encoder provides a number of incremental movement signals which can be counted by the processor and compared with a preselected distance proportional to the spacial relationship between the initial position and the selected loading zone.
Finally, the method of the present invention may include the steps of loading a First-In, First-Out (FIFO) register with the locations of the tortilla stacks as they arrive in the stack supports. Essentially, the tortilla stacks are loaded and unloaded in a first-in, first-out fashion, so that, as the FIFO register is unloaded, the tortilla stacks are also unloaded onto the conveyor blocks in the same order they arrive at the stack supports.